Vacuum responsive device



June 18, 1968 C. wHn-ING 3,388,682

VACUUM RESPONS IVE DEVICE Filed March 4, 1965 H -ngz I United States Patent O 3,388,682 VACUUM RESPONSIVE DEVICE `lames C. Whiting, Royal Oak, Mich., assignor to Michigan-Dynamics, Inc., Detroit, Mich., a corporation of Michigan Filed Mar. 4, 1965, Ser. No. 437,130 Ciaims. (Cl. 116-70) ABSTRACT 0F THE DISCLQSURE A vacuum responsive device of the type in Which a diaphragm is exposed to atmospheric pressure on one side thereof and subatmospheric pressure on its other side. The diaphragm carries a slidable stem that serves .as a latch for ball detents. The ball detents lock a Aspring biased signal member. When the diaphragm has moved a given amount in response to a irst level of subatmospheric pressure, the stern will permit movement of a first pair of ball detents out of alignment with a shoulder on the signal member so that the signal member can be moved by its spring to a rst indicating position. Further movement of the diaphragm will unlatch a second pair of ball detents to permit the signal member to be biased to a second indicating position. The two indicating positions may be indicative of an incipient clog iilter conditon and a completely clogged condition, respectively.

This invention relates to vacuum responsive devices of the type in which a diaphragm exposed to a subatmospheric pressure actuates a signal to indicate when the vacuum has exceeded a predetermined level.

One of the principal objects of this invention is to provide a device of this type which has a two-stage signalling function and in which two signalling media are successively presented in response to movement of a diaphragm. The movement of the signal is controlled by detents or ball-like members which are, in turn, actuated by the diaphragm.

While the commercial uses to which the present invention is adaptable are numerous and widespread, it iinds particular utility in connection with the hydraulic power systems of machine tools and the like. The device may be connected between the lter of a fluid reservoir and the pump. With such an arrangement, the device will indicate if the l'ilter or tluid supply line has 4become clogged up or the flow of iiuid is impeded so that a correction should be made. Broadly stated, the device is useful in any vacuum or suction line where an excessive vacuum condition is to be avoided.

The various objects of this invention are attained by a vacuum device comprising a vacuum actuated diaphragm having a movable stern attached thereto which stern is adapted to control a plurality of detents. These detents control movement of the signal device in such a manner that the initial movement of the stem releases a first signal and the further movement of the stem, due to a greater vacuum, releases the second signal.

It is an important object of this invention to provide a device of this type which is so reduced in the number and character of its component parts as to approach the ultimate in structural simplicity and which creates an economy in its manufacture, installation and maintenance costs.

The various objects and advantages, and the novel details of construction of one commercially practical embodiment of the invention, will become more apparent as this description proceeds, especially when considered in connection with the accompanying drawings, in which:

FIGURE l is a vertical section through the device with the signal shown in operative position by dot and dash lines; and

FIGURE 2 is a detail sectional view taken substantially on the plane indicated by line 2 2 in FIGURE 1.

The device of this invention comprises a housing which is divided by a rubber diaphragm into upper and lower chambers. The upper :chamber is open to atomspheric pressure and the lower chamber is placed in communication with the liuid medium on which surveillance is to be maintained. The object is to activate a two-stage signal as the level in the vacuum drops. The vacuum (subatmospheric pressure) in the lower chamber, together with the atmospheric pressure in the upper chamber, provides a diiierential pressure condition across the diaphragm which tends to move the diaphragm downwardly. This action is opposed by a coil spring, the tension of which is adjustable. When the spring yields, the diaphragm will move downwardly and carry with it a stem-like member which controls the signal.

The device comprises a housing 10 which consists of an upper housing member 11 and a lower housing member 12 which may be joined together in any suitable manner as, for instance, by means of a ring-like clamping member 13. Also secured at the union between the housing members 11 and 12 is a supporting bracketdike member 14.

The chamber indicated by the reference character 1'5 is open to atmospheric pressure. The reference character 16 indicates a vacuum chamber.

Located between the chambers 15 and 16 is a diaphragm 17 made of some flexible material such, for instance, as rubber. The periphery of this diaphragm is clamped between the edges of the housing members 11 and 12, as shown.

An upward force on the diaphragm 17 is exerted by a spring 18 mounted between washers 19 and 20, and magnitude of the force offered by the spring 18 may be adjusted in any suitable manner as, for instance, by an adjustable screw member 21 threaded into a nipple member 22 provided with threads 23 adapted to be threaded into the conduit for the liuid medium on which surveillance is to be maintained.

The diaphragm 17 is provided with a stem 24 rigidly secured thereto and adapted to move therewith. This stem 24 is adapted to control a signal device 25. The signal device 25 is in the form of a 'button-like member formed in two parts 26 and 27. In order that the extent of the movement of the diaphargm may be visually readily determined, the parts 26 and 27 of the signal device may be of different colors. For instnace, the section 26 may be formed of some yellow material and the section 27 formed of some red material. When the signal is in its operative position, illustrated in FIGURE l, it is clearly visible through a cover t28 formed of clear plastic or some other suitable material which has a snap-on engagement with the top ofthe housing portion 11.

The signal device is fixed to a sleeve 30 so that the parts 25 and 30' move together. Rigidly secured to the bracket 14 is a locking sleeve or retainer 31. Thus, the locking sleeve 31 is iixed against vertical movement. The signal device 25-30 is slidably mounted on this locking sleeve 31 for vertical movement -relative thereto, as viewed in FIGURE 1. The stem 24 connected to the diaphragm 17 slides within the locking sleeve 31 to control the movement of the signal device 25 in a manner yet to be described.

The stem 24 is provided with a main circular portion 35 which is of substantially the same diameter as the inner diameter of the locking sleeve 31 and with an annular portion 36 of substantially the same diameter. Between the `portions 35 and 36, the stern 24 is provided with a recessed or reduced diameter portion 37 and the upper end of the stem 24 has a recessed portion of ren duced diameter, as indicated at 38.

The sleeve of the signal device is provided with an enlarged inner diameter portion forming an annular space or recess 41. The lower end of the reduced portion 40 terminates in an annular shoulder 42 which is normally positioned immediately below the reduced diameter sleeve portion 37.

The signal device 25 is controlled by two pairs 43 and 44 of ball shaped detents or locking members. The detents of each pair are disposed diametrically opposite one another and the two pairs are rotated 90 from one another. These detents 43 and 44 lie in openings 45 in the locking sleeve 31 and are normally caused to project into the recess 41 by the portions 35 and 36 of the stem 24. This is the position of the parts shown in FIGURES 1 and 2.

When, however, the stem 24 is shifted relative to the locking sleeve 31, one or both of reduced portions 37 and 38 is brought radially opposite to or in registration with the detents 43 or 44 so as to release the signal device 25. The reduced portions 37 and 38 are spaced apart axially a slightly greater distance than the detents 43 and 44 so that the detents 44 will move radially inwadrly out of the recess 41 first and thereafter, upon further movement of the stem 24, the detents 43 will move radially inwardly out of the recess 41. The radially inward movement of the detents 43 and 44 is caused by the shoulder 42, the inclined attitude of the shoulder 42 producing a camming action on the balls 43 or 44 as it contacts them.

The signal device 25 is normally biased in an upward direction by means of a spring v which is seated on the Lbracket 14 and engages a flange 51 on the lower end of the signal device. Thus, when the detents 43 and 44 are freed for radially inward movement, the spring 50 will move the signal device upwardly to the positions 27a and 26a, respectively, shown in FIGURE 1.

Upon the initial downward movement of the stem 24, the reduced diameter stem portion 37 is first brought into registration with the lower of said detents 44. This occurs While the stem portion 36 still lies adjacent the detents 43 and keeps the detents 43 projecting into the recess 41 and prior to the time that the reduced diameter stem portion 38 comes into registration with the detents 43. At this point, the inclined shoulder 42 is able to cam the detents 44 transversely or radially inwardly clear of the shoulder 42, freeing the members 2S and 30 for upward movement under the influence of the spring 50 until the shoulder 42 contacts the detents 43. At this point, the signal part 26 will lie above the housing member 11 and assumes a position indicated in broken lines at 27a in FIGURE l. The spring is calibrated so that this first stage of indicator movement will occur at a point slightly prior to the excessive vacuum condition which it is desired to avoid. Thus, a machine attendant observing the preliminary warning given by the section 26 can take the necessary corrective action to remedy the condition producing the vacuum. Such corrective action would normally consist of changing or cleaning a clogged filter. However, if such corrective action is not taken and the condition becomes Worse, a higher level of vacuum of a predetermined degree will result in the diaphragm 17 and stem 24 moving downwardly still further until the reduced diameter stem portion 3S is brought into registration with the detents 43. At this point, the ball detents 43 are freed for transverse or radially inward movement by the camming force of the inclined shoulder 42, thereby permitting the signal member 25 to move axially upwardly until the flange 51 contacts the upper end of housing member 11. At this point, the lower signal part 27 will be exposed and will assume the position shown in 4broken lines at 27a in FIGURE 1. The upper signal part 26 will now have been moved to the position shown at 25a in FIGURE l.

The device of the present invention is believed to be particularly useful in that it provides a warning of an impending excess vacuum condition as Well as an indication of an existing excess vacuum condition, thus allowing corrective action to be taken prior to the occurrence of possible damage or machinery malfunction resulting from the excess vacuum condition. It is believed that the device of thefpresent invention provides such a two-stage warning function with a high degree of accuracy and in a highly expeditious manner.

The cover 28 may be of clear plastic or any other suitable material and snapped into place on the housing portion 11. The portions 26 and 27 of the signal device may conveniently be made of anodized aluminum or colored plastic, or any other suitable material.

It is believed that from the foregoing, the operation and advantages of the device will be readily apparent. As will also be apparent from the foregoing description, the objects and advantages of this invention are attained by a construction which is so reduced in the number and character of its component parts as to approach the ultimate in structural simplicity. The simplicity of the device creates an economy in its manufacture, installation and maintenance costs.

`While one commercially practical embodiment of the invention has been described and illustrated herein somewhat in detail, it will ybe understood that various changes may be made as may come within the purview of the accompanying claims.

What is claimed is:

1. A vacuum indicating device including a housing, a pressure responsive member movably disposed within said housing and forming therewith a closed pressure chamber on' one side of said pressure responsive member with the other side thereof exposed to atmospheric pressure, yieldable means biasing said pressure responsive member in a direction opposing the force of atmospheric pressure acting thereon, a stem connected to said pressure responsive member and movable therewith along a given. axis, said stem having first and second axially spaced recessed portions, a signal member, means guiding said signal member for axial movement from a retracted position to first and second indicating positions, a spring biasing said signal member from said retracted position toward said indicating positions, shoulder means on said signal device, first and second detent means, a detent retainer surrounding said stem and operable to hold said detent means in axially spaced positions therealong while permitting radial movement of said detent means between positions in and out of axial alignment with said shoulder, said stem being normally operable to hold said detents in axial alignment with said shoulder, the movement of said stem first recessed portion into radial alignment with said first detent means being operable to permit radial movement of said rst detent means out of axial alignment with said shoulder whereby said signal member is released for movement by said spring from said retracted position to said first indicating position, and the `movement of said second stem recessed portion into alignment with said second detent means being operable to permit radially inward movement of said second detent means out of axial alignment with said shoulder whereby said signal member is freed for movement to said second indicating position.

2. The structure set forth in claim 1 wherein said signal member is of annular configuration and surrounds said stem and wherein the shoulder of said signal mem-- ber is of annular shape.

'3. The structure set forth in claim 1 wherein said retainer has a cylindrical outer peripheral surface and wherein said signal member is provided with a sleeve portion slidably guided on said peripheral surface.

4. The structure set forth in claim 1 wherein said retainer is of sleeve shaped configuration and wherein each of said detent means comprises a plurality of balls movable within openings of said retainer.

5. The structure set forth in claim 1 wherein said signal member shoulder is inclined with respect to the axis of said stem for applying aradially inward force to said detent means to thereby produce radially inward movement of said detent means upon the movement of a stem recessed portion to a position radially opposite thereto.

6 References Cited UNlTED STATES PATENTS 2,843,077 7/1958 Leefer 116-117 2,954,751 10/1960 Barnes 116-70 3,119,367 1/1964 lBarnes etal 116-70 3,200,787 8/ 1965 Darnell 116-70 3,216,571 11/1965 Whiting et al. 210-90 LOUIS J. CAPOZI, Primary Examiner. 

